This invention relates to downhole jet pumps having provisions by which high velocity power fluid is forced through a nozzle into a throat area which creates a suction in its wake. This invention provides an advantage over the present known jet pumps by the employment of a variable throat design having a deflector device which utilizes the normally wasted fluid motion located in the center of the jet stream.
The deflector device deflects the total fluid in the jet stream radially outwardly against the variable throat area in proportion to the pressure exerted by the surface power unit used to supply the power fluid to the jet nozzle. The greater the pressure exerted on the jet stream exiting the nozzle, the further up the deflector the suction action will occur. As the suction area in the variable throat is increased, the wake suction action also is increased.
The use of this type throat design allows employment of a larger diameter throat opening than was previously possible, while retaining a high efficient pumping action, all of which is a great advantage over other jet type pumps.
Another advantage of the deflector is to put the wasted fluid motion to work. As the deflector is moved back towards the nozzle, the fluid is deflected into a cone shaped mist, and it is this cone shaped mist action which is used to create the suction in the variable throat.
Since this throat does not employ any straight internal surface area in its bore, it is unlike any known jet pump which uses a deflector of any type.
The deflector throat relation of 10.degree.-15.degree. mentioned herein is merely a suggested figure and may vary according to the size of the pump and the volumes demanded. These angles may be changed according to the particular pump design and operational perimeters.